\documentclass[a4paper,12pt,reqno]{article}

\usepackage[T1]{fontenc}
\usepackage{authblk}
\usepackage{graphicx,color,xcolor}
\usepackage{amsthm,amsmath,amssymb,amsfonts}
\usepackage{pgf,tikz}
\usepackage{mathrsfs}
\usetikzlibrary{arrows}
\usepackage{color,xcolor}
\usepackage[top=3.5cm,right=3cm,bottom=2.5cm,left=2.5cm, headheight=60pt ,headsep=1cm]{geometry}
\usepackage{hyperref}
\usepackage{fancyhdr}
\begin{document}

\begin{figure}[!ht]
	\centering
		\definecolor{cqcqcq}{rgb}{0.7529411764705882,0.7529411764705882,0.7529411764705882}
		\definecolor{ffcqcb}{rgb}{1.,0.7529411764705882,0.796078431372549}
		\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
		\clip(2.92,-0.9) rectangle (7.76,3.76);
		\fill[line width=2.pt,color=cqcqcq,fill=cqcqcq,fill opacity=1.0] (5.,3.) -- (4.,3.) -- (4.,1.) -- (5.,0.) -- (7.,0.) -- (7.,1.) -- cycle;
		\draw [line width=2.pt,color=cqcqcq] (5.,3.)-- (4.,3.);
		\draw [line width=2.pt,color=cqcqcq] (4.,3.)-- (4.,1.);
		\draw [line width=2.pt,color=cqcqcq] (4.,1.)-- (5.,0.);
		\draw [line width=2.pt,color=cqcqcq] (5.,0.)-- (7.,0.);
		\begin{scriptsize}
		\draw [fill=ffcqcb] (5.,3.) circle (2.5pt);
		\draw [fill=ffcqcb] (4.,3.) circle (2.5pt);
		\draw [fill=ffcqcb] (4.,1.) circle (2.5pt);
		\draw [fill=ffcqcb] (5.,0.) circle (2.5pt);
		\draw [fill=ffcqcb] (7.,0.) circle (2.5pt);
		\draw [fill=ffcqcb] (7.,1.) circle (2.5pt);
		\draw [fill=ffcqcb] (4.,2.) circle (2.5pt);
		\draw [fill=ffcqcb] (5.,2.) circle (2.5pt);
		\draw [fill=ffcqcb] (6.,2.) circle (2.5pt);
		\draw [fill=black] (5.,1.) circle (3.0pt);
		\draw [fill=ffcqcb] (6.,1.) circle (2.5pt);
		\draw [fill=ffcqcb] (6.,0.) circle (2.5pt);
		\end{scriptsize}
		\end{tikzpicture}
		\caption{$S_2(2,1)$ in $\mathbb{Z}^2$}
	\hspace{1cm} 
	\centering
	\definecolor{cqcqcq}{rgb}{0.7529411764705882,0.7529411764705882,0.7529411764705882}
	\definecolor{ffcqcb}{rgb}{1.,0.7529411764705882,0.796078431372549}
	\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
	\clip(2.04,0.24) rectangle (5.88,3.52);
	\fill[line width=2.pt,color=cqcqcq,fill=cqcqcq,fill opacity=1.0] (4.,3.) -- (3.,3.) -- (3.,2.) -- (4.,1.) -- (5.,1.) -- (5.,2.) -- cycle;
	\draw [line width=2.pt,color=cqcqcq] (4.,3.)-- (3.,3.);
	\draw [line width=2.pt,color=cqcqcq] (3.,3.)-- (3.,2.);
	\draw [line width=2.pt,color=cqcqcq] (3.,2.)-- (4.,1.);
	\draw [line width=2.pt,color=cqcqcq] (4.,1.)-- (5.,1.);
	\draw [line width=2.pt,color=cqcqcq] (5.,1.)-- (5.,2.);
	\draw [line width=2.pt,color=cqcqcq] (5.,2.)-- (4.,3.);
	\begin{scriptsize}
	\draw [fill=ffcqcb] (4.,3.) circle (2.5pt);
	\draw [fill=ffcqcb] (3.,3.) circle (2.5pt);
	\draw [fill=ffcqcb] (3.,2.) circle (2.5pt);
	\draw [fill=ffcqcb] (4.,1.) circle (2.5pt);
	\draw [fill=ffcqcb] (5.,1.) circle (2.5pt);
	\draw [fill=ffcqcb] (5.,2.) circle (2.5pt);
	\draw [fill=black] (4.,2.) circle (3.0pt);
	\end{scriptsize}
	\end{tikzpicture}
	\caption{$S_2(1,1)$ in $\mathbb{Z}^2$}
\end{figure}
\end{document}